Who was primarity responsible for the cold war

Do you mean individual person or nation or both.

Both the USSR and USA could be considered responsible, while speaking of individuals, Joseph Stalin could be considered as an answer.

The soviet union

Explanation:

The soviet union were thought to be at fault for starting the cold war by many historians at the time of the cold war. The reason for this is because the Soviet Union were known to be infiltrating liberated countries and forcing communism upon them which aggravated the western powers.